/* Copyright 2012 The Netty Project
 * 
 * The Netty Project licenses this file to you under the Apache License, version 2.0 (the "License"); you may not use
 * this file except in compliance with the License. You may obtain a copy of the License at:
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License. */
package io.netty.example.proxy;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelOption;

public class HexDumpProxyFrontendHandler extends ChannelInboundHandlerAdapter {

	private final String remoteHost;
	private final int remotePort;

	private volatile Channel outboundChannel;

	public HexDumpProxyFrontendHandler(String remoteHost, int remotePort) {
		this.remoteHost = remoteHost;
		this.remotePort = remotePort;
	}

	@Override
	public void channelActive(ChannelHandlerContext ctx) {
		final Channel inboundChannel = ctx.channel();

		// Start the connection attempt.
		Bootstrap b = new Bootstrap();
		b.group(inboundChannel.eventLoop()).channel(ctx.channel().getClass())
				.handler(new HexDumpProxyBackendHandler(inboundChannel)).option(ChannelOption.AUTO_READ, false);
		ChannelFuture f = b.connect(remoteHost, remotePort);
		outboundChannel = f.channel();
		f.addListener(new ChannelFutureListener() {
			@Override
			public void operationComplete(ChannelFuture future) {
				if (future.isSuccess()) {
					// connection complete start to read first data
					inboundChannel.read();
				} else {
					// Close the connection if the connection attempt has failed.
					inboundChannel.close();
				}
			}
		});
	}

	@Override
	public void channelRead(final ChannelHandlerContext ctx, Object msg) {
		if (outboundChannel.isActive()) {
			outboundChannel.writeAndFlush(msg).addListener(new ChannelFutureListener() {
				@Override
				public void operationComplete(ChannelFuture future) {
					if (future.isSuccess()) {
						// was able to flush out data, start to read the next chunk
						ctx.channel().read();
					} else {
						future.channel().close();
					}
				}
			});
		}
	}

	@Override
	public void channelInactive(ChannelHandlerContext ctx) {
		if (outboundChannel != null) {
			closeOnFlush(outboundChannel);
		}
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
		cause.printStackTrace();
		closeOnFlush(ctx.channel());
	}

	/**
	 * Closes the specified channel after all queued write requests are flushed.
	 */
	static void closeOnFlush(Channel ch) {
		if (ch.isActive()) {
			ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
		}
	}
}
